1. Field of the Invention
The present invention particularly relates to a post-fixing support unit using a corrugation roller as a sheet discharge roller and an image forming apparatus using the post-fixing support unit.
2. Description of the Related Art
Generally, a toner image forming means of an electrophotographic type includes a photoconductor serving as an image carrier and having a photosensitive layer on the outer circumferential surface thereof, a charge means for uniformly charging the outer circumferential surface of the photoconductor, an exposure means for selectively exposing the uniformly charged outer circumferential surface to form an electrostatic latent image, and a development means for supplying toner which is developer to the electrostatic latent image formed by the exposure means to form a visible image (toner image).
As an image forming apparatus of a rotary type for forming a color image, there is known an intermediate transfer belt type color image forming apparatus, in which the toner image forming means as described above is disposed opposite to an intermediate transfer belt. In this configuration, toner images on the photoconductors formed by the toner image forming means are sequentially transferred onto the intermediate transfer belt to superimpose toner images of a plurality of colors (e.g., yellow, cyan, magenta, and black) on the intermediate transfer belt, whereby a color image is obtained on the intermediate transfer belt.
As a sheet discharge unit of the image forming apparatus having the configuration described above, there is known one in which there is provided a means for forcibly forming a surface corrugation on a completed hard copy at the sheet discharge position so as to increase the strength of the recording medium (refer to JP-A-8-324863).
Further, there is known a discharge unit provided with a plurality of driven rolls which are supported by a rotary shaft so as to be rotated independently of a plurality of discharge rolls and each of which has a diameter larger than each of the discharge rolls (refer to JP-A-2004-189368).
In the inventions disclosed in JP-A-8-324863 and JP-A-2004-189368, corrugation rollers are used to cause width direction waving on a recording sheet to increase the strength of the recording sheet, thus ensuring stackability thereof. However, in this environment, when a change of the sheet discharge direction to the face-down direction in a space-saving type system is carried out, curves are generated in two directions on the recording sheet, with the result that folding, puckering, wrinkling, and the like are generated on the recording sheet.